Tucker Roussin, 3, is the first survivor of fetal surgery for a life-threatening tumor connected to his heart. Fetal medicine experts at Children's Hospital of Philadelphia successfully removed this tumor. Credit: Children’s Hospital of Philadelphia.

3-D printed vessel made from living cells implanted in an animal to test feasibility of using such structures clinically. Blood vessels are a stepping stone to the creation of more complex 3-D printed organs made from biomaterials. Image from the South Carolina Project for Organ Biofabrication.